Color control grid structure for cathode-ray tubes



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Sept. 22, 1953 E. o. LAWRENCE 2,653,263

COLOR CONTROL GRID STRUCTURE FOR CATHODE-RAY TUBES Filed Jan. 8, 1952-fullll dlll INVENTOR ERNEST 0. LAME/vb:-

A TTOR/VEYS.

Patented Sept. 22, 1953 COLOR CONTROL GRID STRUCTURE FOR CATHODE-RAYTUBES Ernest 0. Lawrence, Berkeley, Calif., assignor to ChromaticTelevision Laboratories, Inc., San Francisco, Calif., a corporation ofCalifornia Original application February 11, 1952, Serial No. 252,686.Divided and this application January 8, 1952, Serial No. 265,365

12 Claims.

This invention relates to cathode-ray tubes of the character usedparticularly to display images created on the tube target surface underthe control of appropriately applied signal energy. The invention, ofcourse, is applicable to cathode-ray tubes of all general types,including those used for Oscilloscopes, radar installations andmonochromatic television. However, in its principal application it isdirected to certain more detailed aspects relating particularly topolychrome television image reproduction.

For purposes of explaining the invention, the apparatus and tubestructure herein to be set forth and described will be related to a tubeof a variety particularly adapted to the production of tricolor images.The disclosed principles are, however, applicable to more or lesscolors.

In the transmission of signals according to any new proposed system ofcolor transmission, Whether it be field-sequential, line-sequential,segment-sequential or dot-sequential, or even certain varieties of thelatter system developing control signals which, in effect, practicallyamount to simultaneous transmissions, it has become the practice so toregulate the transmissions that all color values are represented bythree primary colors additivcly combined in proper intensity and hue torecreate an image. Reasonably good likenesses of images on correct colorcan be recreated through the use of apparatus of this variety.

Various forms of apparatus for recreating television images in color areset forth and described in co-pending United States patent applicationsSerial Nos. 219,213 and 234,190, filed by this applicant on April 4,1951 and June 29, 1951, respectively, with the said applications beingentitled Cathode-Ray Focusing Apparatus and Direct-View Color Tube.These pending patent applications are particularly concerned withapparatus to recreate tricolor'television images. The apparatus thereset forth is of the cathoderay tube type. It utilizes, among otherfeatures, a principal for accelerating the scanning cathode-ray beam tohigh velocity in the general region of the target under the influence ofa high voltage effective as an accelerator only in that region of thetube. The high impact beam velocity increases the resultant imagebrilliance. Also, through the provision and inclusion of suitableelectrode structure in a region closely adjacent to the target, and theapplication of suitable control voltages, electric fields are developedwhereby the scamiing beam is brought to a high degree of focus as itreaches the target.

at this time.

The beam focusing is actually to a spot size materially smaller thanthat normally realizable under conditions of scanning beam projectiontoward the target.

The target area upon which the scanning beam is disclosed .as'beingprojected is formed of a plurality of phosphor coatings of characterssuch that when activated by the impact of the scanning cathode-ray beam,light in one of the selected additive primary colors is produced by eachseparate phosphor. Phosphors suitable for producing light in such colorsare well known and their specific composition, per se, forms no part ofthis invention or of the companion inventions hereinabove mentioned.

It is also explained in the applications above mentioned, reference towhich is herein incorporated, that the point of scanning cathode-raybeam impact on the target and thus the color of light emission from thetarget is controllable, either by a control of direction of the scanningbeam in its path to the target through the electrode structure adjacentto it, or, alternatively, by the application of suitable controlvoltages on the grid electrode structure adjacent to the target. In thelatter case the scanning beam is displaced relative to the target by asupplementary force over and above that displacement produced by normaldeflection. In either case the scanning beam impacts discrete phosphorcoatings in such manner that the desired color is realized.

The present invention forms an improvement, not onlyupon the electrodestructure for assembly in the region generally adjacent the finalphosphor coated target of the hereinabove-mentioned co-pending UnitedStates applications, but it,is also related to and represents animprovement and refinement of the electrode structure for accomplishingthe stated objectives which are set forth in a concurrently-filed UnitedStates patent application of this applicant which is entitled GridStructure for Cathode-Ray Tubes. Furthermore, the subject matter of thisinvention is related to that set forth in a concurrentlyfiled UnitedStates patent application of James T. Vale, entitled Focusing GridStructure for Electron Tubes, to which reference is also made Thisinvention, in its essence, relates to ways and means by which the gridstructure for use in a. region adjacent to the tube target may be morereadily fabricated and assembled than in heretofore disclosedarrangements. It also represents a form of electrode structure whichprovides suitable Ways and means for alining theconducting strands orwires of the colorcontrcl grid structure relative to the tube target.Still further it offers means for maintaining the alined conductors orstrands in proper relationship relative to the target whereby improvedimage reproduction and greater fidelity of operation is maintained.

Consequently, among the objects of this in vention are those ofproviding a color-control grid structure for use in cathode ray tubes,par-. ticularly of the tricolor variety, which will insure theproduction of brighter imagescorrectly allo cated to color, andproducible in high detail.

Further than this, the present invention has as one of its objectivesthat of providing a Colorcontrol grid structure for usein-conhectionwith 4 an electron gun comprising at least a cathode, a controlelectrode and an accelerating anode (none of which are shown, forreasons of drawing simplification) to form and accelerate a cathode ray.beam schematically represented at !9. The velocity imparted to theelectrons forming the cathode ray beam as it leaves the gun is suffi-'cient to cause it to move through the tube in the trio circuit for theapplication 01" control and siga phosphor-coated target of a cathode-raytubeduced cost relative to proposals heretofore made.

It is also an object of the invention to provide a color-control gridstructure for use in a cathode ray tube designed to provide multicolorimages wherein the duty cycle of operation may be maintained highwithout resultant color contamination in the finally-produced image.

A further object of the invention is to provide a color-control grid inwhich alinement of the grid conductors with the phosphor target coatingis easily obtained.

Still other and further objects and advantages of the invention will, ofcourse, become apparent from a reading of the following specificationand appended claims connection with the accompanying drawings, wherein:

Fig. 1 represents a cathode-ray tube of the tricolor variety inelevation and partly in section, to show the arrangement of thecolor-control grid of the instant invention relative to the phosphorcoated target and viewing window of the tube;

2 is an end view of the tube of Fig. 1 taken color-control gridstructure of Fig. 2 taken along the line 33 and looking in the directionof the arrows. This view is to show particularly the cantilever-typesupport for the various grid conductors;

Fig. 4 is a plan view of the color-control grid conductor cantileversupport looking downward upon the section shown in Fig. 3; and

Fig. 5 is an isometric showing of a portion of the color-control gridconductor support at the upper end looking through a section thereofgenerally along a line to the left of the line 33 and continuing for alimited number of supported conducting strands.

Referring now to the drawings for a further understanding of theinvention, the cathode-ray tube 1 l comprises the usual tube neckportion 33 and a somewhat bulbous or frusto-conical end portion whichterminates in a flattened viewing window H, as is well known. Theviewing window I1 is a transparent vitreous material. The remainder ofthe tube may be of like character materiahalthough, in some instances,it is desirable that the 'frusto-conical tube portion be formedaccording to well established practice as a metal sidewall secured tothe glass Viewing window I! and the neck portion I3, which is alsousually of glass. As is well known in practice, the complete tubeenvelope is highly evacuated,

and there is provided in the neck portion thereof halling voltages toselected electrode elements.

The center pin 22 of the base is used to position the tube in wellknownmanner in the supporting socket (not shown).

The electron beam developed within the tube is controlled both as to itsinstantaneous impact position at the target and its path of sweep inboth horizontal and vertical directions, as is well known, by magneticdeflecting coils formed into the yoke (not shown) which is arranged tosurround the neck of the tube in the region whereat the tube neck mergeswith the frusto-conical sidewall. Alternatively, the developed electronbeam 59 may be deflected by the aid of electrostatic deflecting means,as is particularly represented in the hereinabove=identified copendingUnited States patent application Serial No. 234,- 190, which likewiseschematically represents the magnetic deflection means.

As the scanning cathode-ray beam 19 is moved longitudinally of the tube,it is arranged ulti-' mately to impact a phosphor-coated targetschematically represented at 23, which is observed through the viewingwindow ll. The phosphorcoated target, as is explained in all of theabovementioned co-pending applications, preferably comprises a series ofstrips of phosphor coatings, all adapted to become luminescent underelectron beam. impact to produce colored images. in the preferred formof arrangement, the strips have one dimension which is but a fraction ofthat oi? the elemental areas into which an image may "be assumed to bedivided for the purpose of pro duction according to all acceptedtelevision operational standards. The phosphor strips may be assumed torepeat in any desired and selected color cycle chosen from amongsuitably selected primary colors of red, blue and green, whichconstitute the generally accepted primaries additive to produce whitelight.

For the purpose of developing high-detail color television images,asexplained in the above-mentioned co-pending United States patentapplications, the phosphors are arranged in cyclically repeatingsequences so that in one dimension at least they repeat at least oncefor each spot or elemental area of the final electro-optical image to berecreated. As such, the phosphor strips may be selected in a repeatingcolor cycle to include red, green and blue, with the width of eachthereof. Suiiice it to say, for illustrative purposes, that any selectedcyclically repeating sequenoe of'the phosphor strips in one dimension issuch that when activated by the scanning cathode ray beam efiective overan area equal to one picture point shall all become luminescent. Eachseparate phosphor-coated strip develops light in one of the colors of anadditive tricolor pattern, assuming, of course, that signal modulationresults on the impacting scanning cathoderay beam as it reaches eachindividual phosphor, and the image point color representation is thenestablished.

For convenience, it is often desirable to form the phosphor-coatedstrips in such fashion that the phosphors to produce red and blue lightare twice as wide as those used to produce green light. Under suchcircumstances, a sequence of phosphor strips may be assumed to comprise,illustratively, a strip to produce green light, a double-width strip toproduce red light, a strip to produce green light, and a double-widthstrip to produce blue light, after which the sequence repeats. A groupof phosphor strips of this character has a width equal to that of twoelemental areas or picture points of the image to be reproduced. It willbe seen, however, that the same three primary colors are present foreach point, with the color cycle, under these circumstances, comprisingred, green, blue, for one spot or point, and blue, green, red for theadjacent spot or point, after which the color cycles and sequence repeatin the stated order. However, since the phosphor strips are each ofsub-elemental width and a portion of each wider strip may be consideredas included in each color cycle, since, in the example assumed, theprecise arrangement is of no moment; the significant factor is that foreach elemental picture point width there is a sub-elemental widthphosphor strip representative of each color, assuming, of course, thatthe elemental area begins and terminates at an intermediate point oneach of the wider strips.

In the assembly of the tube for one suitable scanning cathode-ray beamis adapted to traverse, in its rapid deflection path, the phosphorcoatedstrips in their short dimension, so that in the completion of scanningof each raster the :scanning beam traverses longitudinally the targetstrips from one end to the other.

According to usual tube practice, the phosphor coatings have thereoveron the side toward that from which the cathode-ray beam emanates, analuminum film coating or covering the phosphors. The aluminum filmserves to provide a conducting electrode at the target area, aswell asto function in well known manner to eliminate the detrimental effects ofthe ion spot which would otherwise be present on the tube target. Thecoating also aids in the intensification of the resultant image due tothe fact that the reflecting aluminum film or coating through which thescanning cathode ray beam passes to reach the phosphor serves as a lightreflector, with a result that substantially all light emanating from thephosphor coating is directed outwardly of the tube according to wellknown practice.

The grid with which this present invention is particularly concerned issupported on a framework comprising a pair of spaced beams 25 and 25,separated from one another by spacers 2'! and 23. The support frameformed by the combine. tion of the beams 25 and 26 and the spacers 21and 23 defines the limiting boundaries of the window area in which thetarget is to be viewed.

It will be observed that this area exceeds slightly that of the coatedtarget area 23, as becomes particularly apparent from the showing ofFigs. 1 and 2, although this is illustrative and not a limiting featureof the invention.

The target area 23 is held tightly to the support beam 25 by an upperbracket 29. It is secured to the lower beam 26 by a similar bracket 30.If desired, a plurality of brackets of this nature may be interposedalong the edges of the target 23 and the beams 25 and 26. Similarbrackets 33 are used to secure spacers 27 and 28 relative to the edge ofthe target area 23.

Within the boundaries of the support beams 25 (and the construction ofthe beam 26 will be mentioned only incidentally in what is to follow),there is preferably located a plurality of comblike cantilever strips 35and 31. These cantilever strips are preferably formed from insulatingmaterial. They are confined within a more or less U-shaped section 38 ofthe beam 25 and separated one from the other by a suitable supportbracket 39, tightly wedged therebetween and securely holding theinsulating cantilever strips 35 and 31 into the channel formed in thebeam 25 by the U-shaped configuration. The beam 25 is securely held tothe bracket 29 by any desired form of fastening means, such as theindicated screws 4|, which may also serve as a part of the adjustingmechanism.

The cantilevers 35 and 31 secured to the upper beam 25 are formed with aseries of teeth 43, which are of generally flattened V-shape, and whichare spaced from each other by V-shaped openings 54 (see particularlyFig. 5). The outer ends of the flattened V-shaped teeth have grooves orrecesses 47 extending laterally thereof. At the base of the teeth, andbetween and substantially intermediate the flattened portion of adjacentteeth, conductor-locating pins 49 are positioned. The pins 49 extendtransversely of the cantilever strip and preferably have a generallyL-shaped head thereon, with the open end of the L facing away from theslotted end of each tooth. As will later appear, this forms a convenientway to locate and anchor the conductors to be described. The lowercantilever element 37 constituting the inner one with respect to thebeam 25 is of similar construction, with the flattened V-shaped teeth 5|notched at the outer ends at 53. Pins 55, similar to the pins 49, aresupported on the cantilever strip intermediate adjacent teeth.

The teeth 53 of the innermost cantilever strip 3? are arranged toprotrude outwardly in the spaces between adjacent teeth 43 of the outeror upper cantilever strip 35. This likewise provides an arrangementwhere the upper teeth 53 are located intermediate the lower teeth 5|.The opposite side of the support frame is similar constructed andconsequently need not be discussed in detail. 7

After the cantilever strips 35 and 31 have been located within theU-shaped channel section 38 of the beam 25, a suitable conducting strandin the form of wire, preferably of hardened steel or nickel, and of asize of the order of only 2 or 3 mils (0.002" to 0.003") is arranged tobe strung between the various cantilever elements and across the windowarea. In the assembly of .the structure, a suitable conducting wire orstrand such as that represented at 51 is first strung back and forthbetween the innermost strips. This wire is anchored about opposite pins55 and arranged to pass from one pin over one of the the cantileverfromwhich point it is strung to overlap the flattened tooth end of :theopposite cantilever strip, after which-it is wrapped about a locatingpin positioned in a relative location to the cantilever tooth somewhatlike that shown for except that it is laterally displaced-bye, distancerepresenting the space between adjacent teeth. The process of wrappingback and forth for the innermost of the two cantilever strips isrepeated until a strand of wire isstrung between opposite ends of theassembly. The plan of wrapping is clearly shown by Fig. 5. With thecompletion of the wrapping and securement of a conducting strand or wiretothe inner cantilever strip a wire fastening-to the outer (upper inFig. 5) cantilever strips is'established. The wire or conducting strand:59 is secured to one of the outer "cantilever strip 35 and wrappedabout the anchoring pins 49, andthence over the edges of theoutwardly-extending teeth 43 to be located by the grooves '41 in the endthereof. This Wrapping back and forth and further stringing or" theconducting strand is carried from one edge of the cantilever strip totheother. An examination of the showing of Fig. 5 will indicate that theconducting-strands or wires 51 and 59., when so positioned relative tothe teeth of the comb-like cantilever strips, alternate in position onewith respect to the other, so that the support for one wire is from theinner cantilever strips, while the wire adjacent thereto on either sideis supportedirom the outer cantilever strips. Thenext succeeding wiresare supported from the inner cantilever strips, 'and so on. In theillustrated form of color control grid the cantilever strips have teethseparated by a distance corresponding to two ,pictureelementaso thatbyalternating the position of the-teeth with respectto each other andhavingtheprotruding tooth of the adjacent cantilever strip project "inthe space intervening, the wires 5''! and :59, when strung between thecantilever strips'supported "by the opposite beams25 andZB may be spacedfrom each other by a spacing corresponding to the width of a singleimage pointor picture element to 'be traced=upon the target area.

By locating the cantilever strips in TfiXBd .position relative tooneanothen-andspacing the teeth thereof "equidistant :from each other,it is apparent that-the strung wires 51 and 59 will all be positionedequidistant and parallel ene'with respect to the other. The insulatingcantilever strips (for which various forms of ceramics or vitreousplastics .are suitable) have vsumciently high resilience to hold thewires, when strung, under tension. Then, by initially stringing the wirerather tightly between the teeth and anchoring it about the pins at thebase-oi --.each tooth, it can be appreciated that the cantilever formedbetween the outer edge of each -.tooth, constituting'the free end of thecantilever, :and the support beam (constituting the base or anchor)providessufilcientresiliency continually to hold the strung wires tautto maintain :sub- 'stantially precise parallelism.

The wires astheyiare:connectedatthe ends-oi the strip provide iterminalpoints 16! for con- :necting to the innermost set 51 and terminal point63 forconnectingto :the wires 59 strung to the outermostset-oicantileverstrips 35.

"For the operation .of theztube herein described, it isessentialithatwhestrung-wires be maintain'ed in substantially precise:parallelsrelationship with respect :to the phosphor-coated strips 'on@the target 23. :For' this :purpose, suitable: minute adjustments may,be brought about whereby the relative position of the support beams 25and 25 with respect to the brackets 29 holding the target v23 mayprovide for making slight adjustments in the positioning of theconducting strips relative to the edge of the phosphor-coated strips.

In .one preferred form of operation of the here indescr-ihed electrode,the conducting wire strip preferably is-centr a-lly positioned relativeto the assumed double-width phosphor strips which produce blueand redlight, respectively. Under these conditions of Qperation, the aluminumfilm coating on the target strip may be provided with a suitable highvoltage applied relative to the cathode (not shown) of the electron gun,which voltage is applied in a positive sense to the coating relative'tocathode at the terminal point 55. If, for instance, the target ismaintained at a voltage relative to the cathode which is positive by theorder of approximately 16,000 volts andthe conducting wires 5? and 5.6are maintained at a potential which is negative relative to the finaltarget b some value of the order of about 12,000 volts, it will beappreciated that the scanning .of cathode ray beam i9, after penetratingthe plane of the grid wires 5? as, is nnrnediately subjected to anaccelerating field oi the value of 12,000 volts prior to its reachingthe target area. As explained in the above-mentionedco-pendingapplications, and particularly United States patent application SerialHO. 234,199, this accelerating voltage and the field developed betweenthe target and the grid also brings about a sharp focusing action at thetar get.

To illustrate an embodiment of this tube for the purpose of explainingits operation, it may he assumed that the conducting strands or wires53' and are maintained parallel with ea h other and with an edge of .oneof the phos strips. Also, it may be assumed that the ing between thewires Eii and 55-5 is equal to one picture point. The wires 5i and. 5?)than may be alined with what would constitute the midpcints of each ofthe assumed double-width phosphor strips and extend parallel to the edgeof the strips. If, in this assumed embodime t of the invention, all ofthe conducting strands iii and 3:) are maintained at thesame potentialrelative to the t rget, it maybe assumed that a scanning catl oleeraybeam projected from the electron .gun (not shown) will reach and befocused upon that phosphor strip which is lee-- tween conducting wirestrands 5i and .55. This, then, may be a phosphor to produce greenlight. If new, to produce a .diiierent oolorof light from impact of thescann n cathode ray beam upon the target, it he assumed that the wireswhile maintained. in thegeneral region of 12,690 volts negative relativeto the final target, are, nonetheless,-maintained positiverelative tothe wires iii (by a-voltage difference of, say, 400 to 500 volts, forinstance), the scanning cathode ray beam'directed throughthe wirestoward the tar get will tend to be repelled from the wires 5? .andinovelaterally in the direction-of the wires .59, whereupon, lookin at Fig.5, for instance, it can he assumed that the scanning beam imppacts'thetargetin a position slightly to the left of that which it wouldassumeforall equal potential conducting strands ill and 59. The color of lightwhich will lee-developed .from the impact of the scanning cathode-raybeam-uponthe ;.target'under such conditions is .that due to ac-.tivation of one'of the othertwo phoshors.

Similarly, if the potential relationship between the conductors 51 and59 is suchas to make the conductor positive relative to the conductor 59(in a manner like that explained for conductor 59 relative to conductor51), then the scanning cathode-ray beam may be assumed to move slightlyto the right and to impact the third phosphor to produce the third colorof light. By controlling the instantaneously effective potential on thegrid wires 51 and 59 relative to the target it thus becomes possible toprovide a supplemental deflection of the scanning cathode ray beam inthe region immediately adjacent to the target 23 and to control thereby,as explained,

the position of impact and thereby establish the color of lightdeveloped.

In the foregoing considerations it has been set forth that theparallelly strung color control grid wires are spaced to correspond tothe width of any group of phosphor strips corresponding to.

one color cycle or corresponding to one dimer. sion of a picture pointor elemental area. This reference was particularly for ease ofdescription. In the finally-produced tube it will be appreciated thatthe color-control grid wire spacing is" actually slightly less than theset-forth width of phosphor strips, due to the fact that thecolorcontrol grid is positioned closer to the electron beam source andgun than the final phosphor target. close to the target that the spacingis almost equal to the described width of phosphor strips, but, inpractice, the wire spacing may be regarded as being generally equal tothat fraction of the width of the phosphor strips for each color cyclewhich is represented by the ratio of the distance of the color controlgrid from the virtual electron source to the distance of the target fromthe same virtual electron source.

Thus, within the meaning of what has herein been set forth and as theinvention will be defined in the claims, any reference to identity ofgrid wire spacing and phosphor strip width for one color cycle or eventhe substantial equality thereof shall be understood to include at leastthat degree of tolerance herein stated.

From what has been stated above, it is believed to be apparent that thepresent invention is concerned particularl with that form of gridstructure to bring about the color control, and at the same time toprovide one electrode element for developing the accelerating field toproduce high velocity scanning beam impact upon the target and a sharpfocusing of the beam as it so impinges.

While the invention has been described with respect to one assumedrelationship between the color control grid wires and the assumedtarget, it will be appreciated that this has been done purely forillustrative reasons, and that the invention should be broadly construedand in no way limited to the precise illustration proposed.

The foregoing constitutes a continuation-inpart of co-pendingapplication for, Letters Patent of the United States, Serial No.252,686, filed by present applicant on October 23, 1951, and alsoentitled Color Control Grid Structure for Cathode-Ray Tube.

Having now described the invention, what is claimed is:

1. An electrode structure for a cathode-ray tube comprising a supportframe having spaced beams defining the limiting boundaries of a windowarea, a comb-like cantilever extending outwardly from each spaced beam.conductin The color-control grid is actually so;

strands strung between the teeth of the cantilevers to extendtransversely of the window area, means located substantially at theouter end of each comb-tooth for positionally locating the strungconductors in substantially precisely parallel paths equally spaced fromeach other, and means to connect said strung strands to an electriccircuit.

2. The electrode structure claimed in claim 1 wherein the conductingstrands comprise a continuous member strung back and forth betweenopposite cantilever teeth.

3. The electrode structure claimed in claim 2 comprising, in addition,means located substantially at the plane of the base of the cantileverteeth and between each tooth for anchoring the conducting strandsbetween the points of location thereof by the teeth.

4. An electrode structure for a cathode-ray tube comprising a supportframe having spaced beams defining the limiting boundaries of a windowarea, a comb-like cantilever of insulating material extending outwardlyfrom each spaced beam, conducting strands strung between the teeth ofthe cantilevers to extend transversely of the window area in planessubstantially normal to the plane of the comb-like cantilevers, means atthe outer end of each comb-tooth for positionally locating the strungconductors in substantially precisely parallel paths equally spaced fromeach other, means located generally at the plane of the base of eachcomb tooth and between each tooth to another the strung strands andterminal means to connect said strung strands to an electric circuit.

5. The electrode structure claimed in claim 4 wherein a singleconducting strand is strung back-and-forth between the oppositecantilever teeth, and wherein each comb tooth has a grooved recess atthe outer end extending in a direction coinciding substantially withthat of the conducting strand path between opp-osite cantilever teeth.

6. The electrode structure claimed in claim 5 wherein the anchoringmeans comprises an anchor pin located between each tooth and extendingoutwardly from the comb base in a plate approximately parallel to thatof the conducting strands across the formed window area.

'7. An electrode structure for a cathode-ray tube comprising a supportframe having spaced beams defining limited boundaries of a window area,a plurality of comb-like cantilevers extending outwardly from eachspaced beam, said cantilevers associated with each beam having the teeththereof laterally displaced so that the teeth of one cantilever protrudeoutwardly in the space separating the teeth of the adjacent cantilever,the cantilevers secured to opposite beams being symmetrically positionedrelative to each other, a conductor strung between the teeth of each ofthe comb-like cantilever elements, and terminal means connected to theconductors.

8. An electrode structure for a cathode-ray tube comprising a supportframe having a pair of spaced beams defining limited boundaries of awindow area, a plurality of spaced comb-like cantilevers extendingoutwardly from each spaced beam, the teeth of the cantilevers associatedwith each beam being laterally displaced relative to the teeth of theadjacent cantilever and outwardly from the beam extending in the spaceseparating the teeth of the adjacent cantilever so that the sets ofteeth are interleaved, the

cantilevers secured to opposite beams being symmetrically positionedrelative to each other, a conductor strung between the teeth of each ofthe comb-like cantilevers similarly located relative to the spacedbeams, and terminal means adapted for connecting the separate conductorsto an electrical circuit.

9. The electrode structure claimed in claim 8 comprising, in addition,means to anchor the conducting strands between each tooth or thecantilever.

10. The electrode structure claimed in claim 8 comprising, in addition,means to maintain the sets of conductors electrically separated fromeach other.

11. The electrode structure claimed in claim 8 comprising, in addition,means to maintain each set of conductors substantially coplanar.

12. An electrode structure for a cathode-ray tube comprising a targethaving thereon a plurality of strips of phosphor coatings, each coatingbeing sub-elemental extent in at least one dimension, the phosphorcoatings being adapted to become luminescent under cathode ray beamexcitation to produce light, the several phosphors being adapted toluminesce in individually ones of a plurality of component colors of anadditive polychrome system, and wherein the difierent forms of phosphorcoatings repeat in cyclic succession in at least one direction withinone dimension of a picture image area of elemental size, a

12 support frame having spaced beams defining limiting boundaries of awindow area including substantially the phosphor-coated target, acomblike cantilever extending outwardly from each spaced beam, aconducting strand strung between the cantilever teeth to extendtransversely of the window area, means located generally at the end oreach tooth for po'sitionally locating the strung conductors insubstantially parallel relationship one with respect to the other, meansof alining the conductors relative to one dimension of the phosphorcoatings of the target, said comb-teeth having separations relative toeach other coinciding substantially with the distance represented by thewidth of phosphor coatings of each repeating cycle on the target, andmeans for connecting the conducting strands to an electric circuit.

ERNEST O. LAWRENCE.

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